1. Field of the Invention
The present invention relates to a head slider employed in a recording disk drive such as a hard disk drive (HDD), and in particular, to a head slider comprising an air bearing surface formed on a slider body and a projection defining a tip end higher than the air bearing surface.
2. Description of the Prior Art
A flying head slider is well known in the field of a magnetic disk drive such as an HDD. The head slider flies above the surface of a magnetic disk by receiving airflow generated along the surface when the magnetic disk is driven to rotate. Such a flying head slider usually touches the surface of the magnetic disk when the magnetic disk stands still. It is known as a so-called contact start stop (CSS) control. A head slider suffers from adsorption of a lubricating agent or oil spread over the surface of the disk in the CSS. The adsorption tends to hinder rotation of the magnetic disk at the beginning of the rotation.
It is proposed to form projections or adsorption prevention pads on a flying head slider at the air bearing surface which is opposed to the surface of the magnetic disk. The pads serve to prevent the air bearing surface from contacting the surface of the magnetic disk when the magnetic disk stands still, so that the flying head slider may reduce its contact area to the surface of the disk. This allows less adsorption of a lubricating agent or oil to act on the flying head slider.
It is a trend in the field of magnetic disk drives to employ a so-called Hall-less motor as a spindle motor for driving the magnetic disk. No Hall element is employed in the Hall-less motor. The Hall-less motor thus controls the amount of rotation for the rotor without monitoring or detecting the rotational angle or position of the rotor. The Hall-less motor sometimes suffers from a reverse rotation of the rotation axis when the rotor starts to rotate.
The aforementioned flying head slider takes an inclined attitude during flight, making the outflow end closer to the surface of the magnetic disk. Accordingly, it is necessary to position the projections far from the outflow end or trailing edge of the slider body so as to prevent collision between the projections and the magnetic disk during the flight. Such disposition of the projections causes inclination of the slider body about the tip ends of the projections when the magnetic disk makes a reverse rotation at the beginning of the rotation. The inclination causes the slider body to contact the surface of the magnetic disk at the outflow end in addition to the projections. The effect of meniscus between the slider body and the magnetic disk is intensified so that a larger adsorption is caused between the slider body and the magnetic disk. The magnetic disk sometimes cannot even start to rotate in this situation, because a recent spindle motor transmits less torque to the magnetic disk.
It is accordingly an object of the present invention to provide a head slider allowing a recording disk to normally start to rotate even when a spindle motor causes a reverse rotation.
According to a first aspect of the present invention, there is provided a head slider comprising: a slider body having a leading edge and a trailing edge; a rail formed on the slider body and extending to the trailing edge; a projection formed on the rail; and a rugged surface formed on the rail near the trailing edge.
With the above-described structure, the slider body may be supported on the surface of a recording disk with the projection when the recording disk stands still. The surface of the rail may be spaced apart from the surface of the recording disk. The rail is prevented from contacting the recording disk. The contact area can be reduced between the head slider and the surface of the recording disk. Less adsorption may be transmitted to the head slider from a lubricating agent or oil spread over the surface of the recording disk.
When the head slider inclines downstream around the tip end of the projection in response to a reverse rotation of the recording disk at the beginning of the rotation, the head slider allows the rugged surface to contact the surface of the recording disk at the trailing or outflow end thereof. The effect of meniscus or adsorption cannot be intensified between the lubricating agent or oil and the slider body. Accordingly, it is possible to reliably avoid failure in starting the recording disk to rotate. Less torque of the spindle motor allows the recording disk to normally start rotating.
The rugged surface of the rail may be formed by a higher surface roughness. The rugged surface is in this case made rougher than the remaining surface of the rail. A higher surface roughness is adapted to reduce the contact area between the head slider and the surface of the recording disk. Otherwise, the rugged surface may include at least a stripe of groove carved on the rail, or at least a stripe of swell formed on the rail. The rugged surface likewise serves to reduce the contact area between the head slider and the surface of the recording disk. The groove may extend across the rail in the lateral direction of the head slider.
According to a second aspect of the present invention, there is provided a head slider comprising: a slider body having a leading edge and a trailing edge; a pair of rails formed on the slider body and extending from the leading edge to the trailing edge; a pair of front projections formed on the rails near the leading edge, respectively; a pair of rear projections formed on the rails at a predetermined distance from the trailing edge, respectively; and a pair of rugged surfaces formed on the rails near the trailing edge, respectively.
The head slider of this type is in general designed to define a passage for airflow between the rails. If the passage is formed to expand in the direction of airflow, it is possible to generate a negative pressure between the slider body and the surface of a rotating recording disk. When the negative pressure is balanced with a positive pressure or lift generated at the surfaces of the rails, namely, air bearing surfaces, the flying height of the head slider can reliably be fixed at the predetermined level during rotation of the recording disk.
On the other hand, when the recording disk stands still, the slider body may be supported on the surface of a recording disk with the projections. Accordingly, less adsorption may be transmitted to the head slider from a lubricating agent or oil spread over the surface of the recording disk in the aforementioned manner. In addition, even when the head slider inclines downstream around the tip end of the projection in response to a reverse rotation of the recording disk at the beginning of the rotation, the effect of meniscus or adsorption cannot be intensified between the lubricating agent or oil and the slider body. It is possible to reliably avoid failure in starting the recording disk to rotate. Less torque of the spindle motor allows the recording disk to normally start rotating.
The rugged surfaces of the respective rails may take any shape, such as a higher roughness, at least a stripe of groove, at least a stripe of swell, in the aforementioned manner.
According to a third aspect of the present invention, there is provided a head slider comprising: a slider body having a leading edge and a trailing edge; a front rail formed on the slider body near the leading edge; a pair of rear rails formed on the slider body and extending to the trailing edge; a front projection formed on the front rail near the leading edge; a pair of rear projections formed on the rear rails at a predetermined distance from the trailing edge, respectively; and a pair of rugged surfaces formed on the rails near the trailing edge, respectively.
The head slider of this type is in general designed to define a passage for airflow behind the front rail between the rear rails. The front rail serves to vertically expand the passage in the direction of airflow. It is possible to generate a larger negative pressure between the slider body and the surface of a rotating recording disk. When the negative pressure is balanced with a larger positive pressure or lift generated at the surfaces of the rails, namely, air bearing surfaces, the flying height of the head slider can further reliably be fixed at the predetermined level during rotation of the recording disk.
On the other hand, when the recording disk stands. still, the slider body may be supported on the surface of a recording disk with the projections. Accordingly, less adsorption may be transmitted to the head slider from a lubricating agent or oil spread over the surface of the recording disk in the aforementioned manner. In addition, even when the head slider inclines downstream around the tip end of the projection in response to a reverse rotation of the recording disk at the beginning of the rotation, the effect of meniscus or adsorption cannot be intensified between the lubricating agent or oil and the slider body. It is possible to reliably avoid failure in starting the recording disk to rotate. Less torque of the spindle motor allows the recording disk to normally start rotating.
The rugged surfaces of the respective rails may take any shape, such as a higher roughness, at least a stripe of groove, at least a stripe of swell, in the aforementioned manner.
Aforementioned head sliders may be employed in a recording disk drive such as a hard disk drive and other magnetic disk drive. Such recording disk drive may further comprise: a recording disk having a plurality of recording tracks; a Hall-less motor connected to the recording disk for rotation; a carriage arm carrying the head slider; and an actuator driving the carriage arm. In addition, a transducer may be formed on the slider body for reproducing and/or recording data from and/or into the recording disk. dr
The above and other objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments in conjunction with the accompanying drawings, wherein:
FIG. 1 is a plan view schematically illustrating an interior structure of a hard disk drive (HDD);
FIG. 2 is an enlarged perspective view illustrating a flying head slider;
FIG. 3 is an enlarged perspective view illustrating a bottom surface of the flying head slider;
FIG. 4 is an enlarged partial sectional view taken along the line 4xe2x80x944 in FIG. 3;
FIG. 5 schematically illustrates a behavior of the flying head slider when the magnetic disk starts to rotate;
FIGS. 6A to 6E are enlarged sectional views partly illustrating a first rail during production of the flying head slider;
FIG. 7 is an enlarged perspective view illustrating the flying head slider comprising first and second rugged surfaces according to another embodiment;
FIG. 8 is an enlarged sectional view partly illustrating the first rail comprising stripes of grooves on the first rugged surface;
FIG. 9 is an enlarged sectional view partly illustrating the first rail comprising stripes of ridges for forming the grooves on the first rugged surface;
FIG. 10 is an enlarged perspective view illustrating the flying head slider comprising first and second rugged surfaces according to a further embodiment;
FIG. 11 is an enlarged sectional view partly illustrating the first rail comprising a stripe of swelling surface on the first rugged surface;
FIG. 12 is an enlarged sectional view partly illustrating the first rail comprising the first rugged surface made of surface roughness; and
FIG. 13 is an enlarged plan view illustrating the bottom surface of a flying head slider according to another embodiment.